Automatic coupling or lock for extension-ladders



No. 607,664. Patented .Iuly I9, |898.

` F. S. SEAGRAVE. AUTOMATIC CUUPLING 0R LOCK FOR EXTENSION LADDERS.

(Application filed Aug. 16, 1897.)

(No Model.)

WITN ESSES 5 INVENTOR er'f Ilwrrnn Smarts PnrnNr Ormea.

FREDERIC S. SEAGRAVE, OF COLUMBUS, OHIO.

AUToMATic coUPLlNc 0R LOCK-FOR EXTENslo-N-LADDERS.

SPECIFICATION forming part of Letters Patent Np. 607,664, dated-July 19, 1898. Application nea August 16,1897. sentire. 648,438. (Numana To all whom it may concern:

Be it known that I, FREDERIC S. SEAGRAVE, a citizen of the United States, residing at Columbus, in the county of Franklin and State of Ohio7 have invented a certain new and useful Improvement in Automatic Couplings or Locks for Extension-Ladders, of which the following is a specification.

My invention relates to the improvement of ladder-couplings of that class which are adapted for the purpose of connecting or engaging extension-ladders.

The objects of my invention are to provide the movable or sliding Aladder-section with an improved lock or coupling which is adapted to be tripped by contact with the first rung of the stationary ladder which is above the coupling and to engage or lock on any rung when desired; to so construct and arrange the parts of my improved lock or coupling as to combine great strength and simplicity of construction and operation; to so arrangethe parts of my device as to obviate any tendency to undue friction or binding of the locking-arm during contact with rungs of' the lower ladder; Vto so construct myimproved coupling and its operating partsas to facilitate its production in a comparatively small form and admit of its being adapted foruse on heavy or comparatively light ladders, and to produce other improvements vwhich will be more specifically pointed out hereinafter. These objects I accomplish in the manner illustrated in the accompanying drawings, in which- Y .Y y

Figure jl is a view in perspective of the lower portion of two united ladder-sections, showin g the application of my improved 'cou pling or loc-l; to the second rung of the lower ladder. Fig. 2 is an outer side or face view of my improved coupling, showing the same in position on the ladder-frame and showing in dotted lines different positions assumed by the parts of my device when in operation. Fig. 3 is a sectional view which for the sake of clearness in illustration is taken on four different planes, as indicated by dotted line a: in Fig. 2. Fig. 4 is an inner side view of the fixed base-plate with the locking or coupling arm or plate removed therefrom, and Fig. 5 is a detail view in perspective of the locking-arm.

Similar numerals refer to similar parts throughout the several views.

In the construction of myimproved ladder coupling or lock I employ a base-platel, one of which is in the manner hereinafter described adapted to be secured to the inner. face or side of each of the parallel side arms 2 of a ladder.

4 represents a trip-lever the cam-head 5 of which has its inner end portion of the nose form indicated at 6, this nosel portion being provided with an outwardly-projecting fulcrum-pin 7. The nose of the cam-head is adapted, as shown more clearly in Fig. `4 of the drawings, to project between projecting lugs or pins 8 and 9, which project from the upper end portion of said plate 1, said lever being supported in this position in the manner hereinafter described. At a point in the upper portion of the plate 1 and below the` lever-head I provide said plate with an outwardly-projecting and tubular fulcrum-pin 10, while in the lower portion of said plate I provide a pin 11 and beneath the 'latter a tubular pin 12, with which is connected the lower end of a suitable spring finger or wire 13, the purpose of which will be shown hereinafter.

14 represents my improved locking or coupling plate or arm, the comparatively narrow upper end portion of which is provided with a pin-opening, which is adapted to receive the outwardly-extending fulcrum-pin 7 of the trip-lever 4. Below this point the arm 14 is fulcrumed, as shown, to the pin 10. The lower portion of the arm'14 is widened rearwardly, and said widened portion terminates in a rearwardly and downwardly extending lock or coupling-iinger 15. In the lower portion of the arm-body I provide a transverse slot 16, which is preferably of the slightlycurved form shown. Through this slot eX- tends loosely the pin 12 ofthe plate 1. As shown more clearly at 18 in Fig. gof the drawings, the locking or coupling 'arm 14 has its body or main portion recessed on its under side, and when said arm is mounted upon the plate 1 in the manner above described the spring-finger 13 exerts a pressure against the outer arm-wall formed by said recess, this contact being shown partly in dotted lines in Fig. 4 of the drawings. It is obvious that the pres- IOO sure of the spring 13 upon said arm-wall must result in the pin 17 being normally retained in the forward or inner end of the slotted opening 16 and the locking-finger 15 being normally supported in the path of the rungs of the lower or stationary ladder 20, between the parallel side frame-pieces of which said ladder-section 3 is adapted to be moved.

The mannerof securing the base-plate 1 in connection -with the ladder-frame consists, preferably, in providing bolts 21, which pass through the parallel frame-arms 2, and thence through the tubular pins 10 and 12, hereinbefore described. The outer ends of these bolts are provided with nuts 22, as indicated.

In order to describe the operation of my improved couplings or locks, we will assume that the upper or sliding ladder 3 is in the relative position with the lower or stationary ladder indicated in Figs. 1 and 2 of the drawings-*that is, the lock-finger at the juncture of its under side and the under side of the arm-body 14 is engaged with and resting upon a rung 23 of the lower ladder. lVhen the locking-arm is in this position, the triplever 4 is, as shown in the drawings, extended between the rung 23 and the next higher rung 24. In order to extend the ladder formed by the combination of the upper and lower or sliding and stationary sections, the laddersection 3 is moved upward by any suitable means, this upward movement resulting in a disengagement of the lock-finger with the rung23 and in a Contact of the trip-lever with the next higher rung 24. This contact of the trip and upper rung results in a depression of the trip to the position indicated at A in dotted lines in Fig. 2. The depression of the trip-lever to the last-described position results, through the turning of the cam-head 5 against the pin i), in throwing the upper end portion of the arm 14 outward to the position indicated in dotted lines at I3 and in throwing the lower portion of said arm 14 outward to the position indicated in dotted lines at C. A continuing upward movement of the upper ladder results in the trip-lever passing the rung 24 and in said trip-lever and locking-arm assuming their normal positions. A second depression or inward movement of the locking-arm, however, occurs when the outer curved surface of the locking-fingers comes into contact with and passes said rung 24. Having passed the latter rung, it is obvious that the locking-arm will again assume its outward position and admit of its engagement with the rung 24 in the manner in which it formerly engaged the rung 23. In case it is not desired to lock the lower ladder upon the next succeeding rung the upward movement and operation of passing the rungs may be continued until that rung with which it is desired to engage the upper ladder is reached.

In lowering the upper ladder it is first necessary to raise said upper ladder until the triplever has passed the next higher rung. A downward movement of the upper ladder is now begun, resulting through the contact of the rung, which we will assume is 24, with the ladder may becontinued to the desired point,

when the operation of again engaging the locking-finger with the next upper rung consists in raising the upper ladder until the locking-finger passes and springsinto engagement with the next higher rung.

From the construction and operation which I have described it will be seen that by the use of my improved lock or coupling the ladder-sections are provided with ,an improved automatic locking lmechanism, by means of which the rungs of the upper ladder may be successively engaged. It will be observed that the locking-arm of my improved coupling is fulcrumed in its upper end portion, thereby. obviatin g that tend ency toward binding or wedging of the locking-finger against the rungs when passing the latter, which is ordinarily encountered in cases where the locking-arm is fulcrumed at a lower point. It will also be seen that the position and arrangement of the trip-lever is such as to cause comparatively slight friction in accomplishing its work of throwing back the projecting arm of the lock. It willalso be observed that the construction of my improved ladder lock or coupling is such as to insure great strength and at the same time admit of its being formed comparatively short and of less material than ordinarily employed for such purposes. I am enabled to produce my improved lock in the short form shown owing to the fact that the locking-'arm and trip-lever work -in opposite directions in lowering the upper ladder, and the distance between the outer ends of said trip and locking-finger when the latter are extended from each other need only be equal or substantially equal to the distance between the rungs from center to center. Attention may be called to the fact that the construction, size, and arrangement of` my improved ladder-lock is such as to admit of its being attached to the ladder-frame immediately above the lower rung of the ladder, whereas in ordinary ladder-coupling constructions it has been found necessary to remove the secon'd rung of the upper-ladder sect-ion to admit of the locking device being placed in position for use; but by my device each rung of the upper-ladder section is utilized. In addition to its use on extensionladders, such as are employed by city fire-departments, and on large and heavy ladders it is evident that my improved lock may be IOO IlO

ladder section, a trip-lever having a calnshaped head eccentrically fulcrumed to said looking-arm and lugs 8 and 9 projecting from said back plate whereby the contact of said trip-lever with the upper or lower side of a rung of the lower ladder results in the lower portion of the locking-arm being thrown inwardly in position to pass a rung, substantially as and for the purpose specified.

' FREDERIC. S. SEAGRAVE.

In presence of- C. C. SHEPHERD,

EDWARD M. TAYLOR. 

